Too much gas every time I drink ?

Ok I always had stomach problems and I promised this winter break I'm going to the doctor. But till then, I'm going to explain: In grades 4th-7th I had problems with my stomach, every time I knew its going to be silence my stomach would growl badly. Now, in 8th grade, the most important one, it stopped. But it came with a bigger problem: I'm full of gas. I have to burp way more than 50-75 times daily. When I'm home I don't even care and my stomach is fine. But as soon as I sit on my chair at school, the problems start. I feel like farting and my stomach does sounds like a balloon exploded. Its embarassing when its silence because people can hear my stomach's sounds. And when I ask the teacher if I can go to the toilet, well.. I go and.. suddenly no more gas in me. But I sit again and it begins again. I found a solution: I mustn't drink water but I might die because I have not to drink water FOR 7 HOURS!!! As soon as I drink anything my stomach makes me eliminate tons of gas... What is my problem? My mom said my uncle had this sort of problem where he would drink stuff and he would eliminate lots of gas and he would frequently get diarheea.. I really want this treated because my exams are the most important and I want to concentrate on my exam not on my stomach... I have to sit 3-4 hours in silence so imagine if I get problems...

Why me? Why I'm the only one... And why does this happen only when I feel like there is silence..? Please don't laugh I'm very serious